Effects of water salinity on emitter clogging in surface drip irrigation systems

Saline water can be used in drip irrigation systems, thus conserving freshwater. However, the emitters used in drip irrigation are easily prone to salinity-related chemical clogging, which has become a barrier to the exploitation and utilization of saline water in this context. We therefore analyzed the behavior and emitter distribution of chemical clogging using a drip irrigation experiment comparing four water salinities (1.0, 2.0, 4.0, and 6.0 dS/m) in the Hetao Irrigation District (Inner Mongolia, China). The results revealed that the clogging parameters (discharge ratio variation [Dra] and coefficient of uniformity [CU]) showed a slow–sharp downward trend under saline water conditions. Salinity had significantly negative, linear relationships with the two clogging parameters. We identified that the chemical clogging process exhibited randomness, but showed regularity where it usually occurred. Three types of chemical clogging process were identified, representing gradual, fluctuating, and sudden reductions in the clogging parameters. The highest risk location for chemical clogging was the end of the laterals, while the main site for sedimentation of the blocking materials was the core flow path of emitters. On the basis of the results, a water salinity of below 4.0 dS/m is recommended as suitable for use in drip irrigation systems.